1. Field of the Invention
This invention relates to the art of buffing, and more particularly to a method and apparatus for mechanized, automated, and uniform buffing or wiping of workpiece surfaces. The invention is especially suited for glaze stain buffing of large workpieces having rough, uneven, or recessed and elevated surfaces such as molded paneling or furniture components.
2. The Prior Art
It is known in the prior art to buff a workpiece surface by contacting the surface with a rotating buffing roll. For their wiping elements, such buffing rolls may have brush bristles, mop-like strings, or cloths. Buffing of the workpiece surface may be needed to achieve a desired surface smoothness or luster, or may be a step in a coating process wherein a glaze stain is applied to the surface, the surface wiped to distribute and penetrate the stain uniformly over the surface and the excess stain subsequently wiped away.
In large scale manufacturing operations, it is desirable to automate a buffing process as much as possible. For small, smooth, flat-surfaced workpieces, simply transporting the workpiece while it is in contact with a fixed-axis, rotating roller may be sufficient. However, when the workpiece is large and the surface irregular, such a simple approach may be inadequate to produce an evenly wiped finish and attain effective buffing contact with all areas of the surface.
One approach to mechanized workpiece buffing is exemplified in U.S. Pat. No. 3,441,968. That patent discloses a buffing machine having eight radially oriented buffing rolls mounted on a rotating turret. Relatively small workpieces, such as automobile wheel discs are individually tangentially conveyed into registration beneath a buffing roll. The rolls and workpieces move together in a circular path over approximately 180 degrees, during which time the workpieces are being spun to improve the finish quality. The workpieces are then tangentially conveyed away from the turret of buffing rolls.
The apparatus of U.S. Pat. No. 3,441,968 is subject to some significant disadvantages and limitations. It requires complex drive mechanisms and gearing to produce the combined orbital revolution and radial rotation of the buffing rolls. Additional mechanism is required to register the workpieces with the buffing rolls and to spin the workpieces beneath the rolls. If the workpieces are large, as with wall panels, it becomes impractical, or even hazardous, to spin the workpieces beneath the moving buffing rolls while maintaining registration. The workpieces exit the machine in the direction opposite the direction of entry, precluding use of the machine in a unidirectional, continuous manufacturing line.
What has been needed is a method and apparatus for workpiece buffing or wiping which is mechanically simple, which is capable of uniformly finishing irregular surfaces, and which is suitable for use in a linear, unidirectional manufacturing line.